In a semiconductor device mounted with a memory, the performance of the memory is extremely important in determining the performance of the semiconductor device. For example, in a semiconductor device mounted with a CPU and a memory, commands to be processed by the CPU and data necessary for the processing need to be stored in the memory. Also, processing by the CPU is progressed by sequential reading of the data in the memory. In other words, in a semiconductor device mounted with a CPU and a memory, in order to achieve higher performance, the CPU needs to be able to handle more complicated processes, and this calls for a high-capacity memory. Furthermore, in a semiconductor device mounted with a memory, the power consumption of the memory accounts for a large share of the power consumption of the semiconductor device, in many cases.
In Non-Patent Document 1, which one of the present inventors co-wrote, an RFID mounted with a CPU and a memory is disclosed. For such an RFID, a difficult performance of achieving both an increase in memory capacity and reduction in power consumption is called for in order to achieve higher performance.
[Non-Patent Document 1]
Hiroki Dembo, et al. “RFCPUs on Glass and Plastic Substrates fabricated by TFT Transfer Technology” IEEE, TECHNICAL DIGEST OF INTERNATIONAL ELECTRONIC DEVICES MEETING, Dec. 5, 2005, pp. 1067-1069.